docs: update documentation for extraction functions migration

- Add ExtractionFunctions.md reference document
- Update database-schema spec with 11 extraction functions
- Update data-access spec to document extraction function approach
- Update search-processing spec with new query builder interface
- Add Database.Tests to Testing.md architecture doc
- Update DataFlow.md with extraction function flow

DOCUMENTATION/Architecture/Testing.md

@@ -5,22 +5,34 @@ The test project uses xUnit for the framework, Shouldly for assertions, and NSub
 ## Project Structure
 
 ```
-JdeScoping.Tests/
-├── Unit/
-│   ├── Services/
-│   │   ├── SearchServiceTests.cs
-│   │   ├── ExcelExportServiceTests.cs
-│   │   └── DataSyncOrchestratorTests.cs
-│   ├── Repositories/
-│   │   └── SearchRepositoryTests.cs
-│   └── Models/
-│       └── SearchCriteriaTests.cs
-└── Integration/
-    ├── ApiTests/
-    │   ├── SearchControllerTests.cs
-    │   └── LookupControllerTests.cs
-    └── RepositoryTests/
-        └── JdeRepositoryTests.cs
+tests/
+├── JdeScoping.Tests/
+│   ├── Unit/
+│   │   ├── Services/
+│   │   │   ├── SearchServiceTests.cs
+│   │   │   ├── ExcelExportServiceTests.cs
+│   │   │   └── DataSyncOrchestratorTests.cs
+│   │   ├── Repositories/
+│   │   │   └── SearchRepositoryTests.cs
+│   │   └── Models/
+│   │       └── SearchCriteriaTests.cs
+│   └── Integration/
+│       ├── ApiTests/
+│       │   ├── SearchControllerTests.cs
+│       │   └── LookupControllerTests.cs
+│       └── RepositoryTests/
+│           └── JdeRepositoryTests.cs
+├── JdeScoping.Api.IntegrationTests/
+│   └── ... (API integration tests)
+└── JdeScoping.Database.Tests/
+    ├── Infrastructure/
+    │   └── DatabaseTestBase.cs
+    ├── Functions/
+    │   ├── ScalarFunctionTests.cs
+    │   ├── SimpleTableFunctionTests.cs
+    │   └── ComplexTableFunctionTests.cs
+    └── Procedures/
+        └── ValidateSearchCriteriaProcedureTests.cs
 ```
 
 ## Unit Tests
@@ -175,7 +187,64 @@ public class SearchRepositoryIntegrationTests : IDisposable
 }
 ```
 
+## Database Tests
+
+The `JdeScoping.Database.Tests` project tests SQL functions and stored procedures against a live SQL Server instance.
+
+### Test Infrastructure
+
+Tests inherit from `DatabaseTestBase` which provides:
+- Connection management via `DatabaseTestFixture`
+- Automatic test data cleanup
+- Helper methods for inserting test searches
+
+```csharp
+[Collection("DatabaseTests")]
+public class ScalarFunctionTests : DatabaseTestBase
+{
+    [Fact]
+    public async Task fn_GetSearchMinimumDt_ValidSearch_ReturnsDateTime()
+    {
+        // Arrange
+        var criteria = new SearchCriteria { MinimumDt = new DateTime(2024, 6, 15) };
+        var searchId = await InsertTestSearchAsync(criteria);
+
+        // Act
+        var result = await Connection.QuerySingleOrDefaultAsync<DateTime?>(
+            "SELECT dbo.fn_GetSearchMinimumDt(@SearchId)",
+            new { SearchId = searchId });
+
+        // Assert
+        result.Should().BeCloseTo(criteria.MinimumDt.Value, TimeSpan.FromSeconds(1));
+    }
+}
+```
+
+### Test Categories
+
+| Category | Tests | Description |
+|----------|-------|-------------|
+| Scalar Functions | 15 | Test `fn_GetSearchMinimumDt`, `fn_GetSearchMaximumDt`, `fn_GetSearchExtractMisData` |
+| Simple Table Functions | 38 | Test array extraction for work orders, items, profit centers, work centers, operators |
+| Complex Table Functions | 23 | Test object extraction for component lots and part operations |
+| Validation Procedure | 6 | Test `usp_ValidateSearchCriteria` error handling |
+
+**Total: 82 database tests**
+
+### Running Database Tests
+
+```bash
+# Run all database tests
+dotnet test tests/JdeScoping.Database.Tests
+
+# Run specific test class
+dotnet test tests/JdeScoping.Database.Tests --filter "FullyQualifiedName~ScalarFunctionTests"
+```
+
+**Prerequisites**: SQL Server must be running on localhost:1434 with the ScopingTool database.
+
 ## Related Documentation
 
 - [Core Project](./CoreProject.md)
 - [Dependencies](./Dependencies.md)
+- [Database](./Database.md)